Blood Rites (The Dresden Files, Book 6)

From the publisher
Harry Dresden, Chicago's only professional wizard, takes a case as a favor to friend-a vampire of dubious integrity-only to become the prime suspect in a series of ghastly murders.

Long Synopsis:

Blood Rites, the sixth book in Jim Butcher's Dresden Files (Storm Front, Fool Moon, Grave Peril, et al.) pits Harry Dresden -- a Chicago detective who happens to be a powerful wizard -- against a mysterious killer who is systematically targeting people working on an X-rated movie set.
When an unlikely acquaintance of Harry's -- a self-absorbed vampire named Thomas -- asks him as a favor to help out a friend, Harry is compelled to agree. The friend, Arturo Genosa, is a motion picture producer in the process of starting his own adult entertainment company. But someone, or something, doesn't want him to succeed. One by one, his employees are dying incredibly gruesome and seemingly accidental deaths. Harry, posing as a production assistant, investigates.
What he uncovers is pure evil. Someone is ritualistically killing members of Genosa's staff with a powerful magic curse that involves raising a demon. As Harry digs deeper, he finds himself in the middle of a deadly vampiric civil war that not only puts his life in danger but also risks the lives of hundreds of innocents. Further probing leads Harry to some jaw-dropping insights, both about the vampires and about himself.
Fans of genre-transcending sagas like Laurell K. Hamilton's Anita Blake novels and Charlaine Harris's Southern Vampire sequence should thoroughly enjoy Butcher's Dresden Files, which are equal parts fantasy, horror, and hard-boiled mystery. Powered by the author's irreverent sense of humor, this tongue-in-cheek supernatural thriller is as entertaining as it is grisly. Jim Butcher definitely puts the "ick" in magic-based fantasy.